This present invention is directed towards devices for cooling. In particular it is directed toward devices for cooling Integrated Circuits, such as high-performance Micro-Processors, VLSI chipsets, Infra-Red imaging sensors, and the like.
In U.S. Pat. No. 6,720,704 diode devices are disclosed in which the separation of the electrodes is set and controlled using piezo-electric, electrostrictive or magnetostrictive actuators. This avoids problems associated with electrode spacing changing or distorting as a result of heat stress. In addition it allows the operation of these devices at electrode separations which permit quantum electron tunneling between them. Pairs of electrodes whose surfaces replicate each other are also disclosed. These may be used in constructing devices with very close electrode spacings.
In U.S. Pat. No. 6,417,060 a method for manufacturing a pair of electrodes comprises fabricating a first electrode with a substantially flat surface and placing a sacrificial layer over a surface of the first electrode, wherein the sacrificial layer comprises a first material. A second material is placed over the sacrificial layer, wherein the second material comprises a material that is suitable for use as a second electrode. The sacrificial layer is removed with an etchant, wherein the etchant chemically reacts with the first material, and further wherein a region between the first electrode and the second electrode comprises a gap that is a distance of 50 nanometers or less, preferably 5 nanometers or less. Alternatively, the sacrificial layer is removed by cooling the sandwich with liquid nitrogen, or alternatively still, the sacrificial layer is removed by heating the sacrificial layer, thereby evaporating the sacrificial layer.
In U.S. Pat. No. 6,774,003 a method for manufacturing a pair of electrodes comprises fabricating a first electrode with a substantially flat surface and placing a sacrificial layer over a surface of the first electrode, wherein the sacrificial layer comprises a first material. A second material is placed over the sacrificial layer, wherein the second material comprises a material that is suitable for use as a second electrode. The sacrificial layer is removed with an etchant, wherein the etchant chemically reacts with the first material, and further wherein a region between the first electrode and the second electrode comprises a gap that is a distance of 50 nanometers or less, preferably 5 nanometers or less. Alternatively, the sacrificial layer is removed by cooling the sandwich with liquid nitrogen, or alternatively still, the sacrificial layer is removed by heating the sacrificial layer, thereby evaporating the sacrificial layer.
In U.S. Patent App. No. 2003/0068431 materials bonded together are separated using electrical current, thermal stresses, mechanical force, any combination of the above methods, or any other application or removal of energy until the bonds disappear and the materials are separated. In one embodiment the original bonding was composed of two layers of material. In another embodiment, the sandwich was composed of three layers. In a further embodiment, the parts of the sandwich are firmly maintained in their respective positions during the application of current so as to be able to subsequently align the materials relative to one another.
In WO03090245 a Gap Diode is disclosed in which a tubular actuating element serves as both a housing for a pair of electrodes and as a means for controlling the separation between the electrode pair. In a preferred embodiment, the tubular actuating element is a quartz piezo-electric tube. In accordance with another embodiment of the present invention, a Gap Diode is disclosed which is fabricated by micromachining techniques in which the separation of the electrodes is controlled by piezo-electric, electrostrictive or magnetostrictive actuators. Preferred embodiments of Gap Diodes include Cool Chips, Power Chips, and photoelectric converters.
In U.S. Pat. No. 3,169,200, a multilayer converter is described which comprises two electrodes, intermediate elements and oxide spacers disposed between each adjacent element. A thermal gradient is maintained across the device and opposite faces on each of the elements serve as emitter and collector. Electrons tunnel through each oxide barrier to a cooler collector, thereby generating a current flow through a load connected to the two electrodes. One drawback is that the device must contain some 106 elements in order to provide reasonable efficiency, and this is difficult to manufacture. A further drawback results from the losses due to thermal conduction: although the oxide spacers have a small contact coefficient with the emitter and collector elements, which minimizes thermal conduction, the number of elements required for the operation of the device means that thermal conduction is not insignificant.
In U.S. Pat. No. 6,876,123 a thermotunneling converter is disclosed comprising a pair of electrodes having inner surfaces substantially facing one another, and a spacer or plurality of spacers positioned between the two electrodes, having a height substantially equal to the distance between the electrodes, and having a total cross-sectional area that is less than the cross-sectional area of either of the electrodes. In a preferred embodiment, a vacuum is introduced, and in a particularly preferred embodiment, gold that has been exposed to cesium vapor is used as one or both of the electrodes. In a further embodiment, the spacer is made of small particles disposed between the electrodes. In a yet further embodiment, a sandwich is made containing the electrodes with an unoxidized spacer. The sandwich is separated and the spacer is oxidized, which makes it grow to a required height whilst giving it insulatory properties, to allow for tunneling between the electrodes.
There is a need in the art for devices having the simplicity of a layered structure to provide electrode separation without the use of active elements, in which problems of thermal conduction between the layers is reduced or eliminated.